JPS6044810A - Device for detecting position of spot light - Google Patents

Abstract

PURPOSE:To decrease the effect of the secondary reflection, by projecting light to a material to be measured, detecting the projecting direction of the spot light, which is scanned in two dimensions, and sequentially selecting one-dimensional photoelectric elements based on the detected data of a spot-light-image detecting means. CONSTITUTION:Motors connected to reflecting mirrors 13 and 14 are driven by driving circuits 17 and 18. Thus spot light images 5 are scanned on a work 4 in two dimensions. The light projecting direction of the spot light detected by a means III. In this means, the rotary angle of the reflecting mirror 14 is detected by a detector 19. The result is converted into a signal required for the control of a circuit 21 in the next state. A spot-light-image detecting means IV is constituted by arranging an optical lens 22 and a plurality of one-dimensional photoelectric elements 23. Then the one-dimensional photoelectric elements 23 are sequentially selected by a sensor output selecting means based on the output signal of the means III.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a spot light position detection device that is used as a visual sensor for an industrial robot or as a non-contact sensor for inspecting the shape, dimensions, and position of an object. It is related to.

Conventional configurations and their problems Various types of sensors 1 are used to automate and unattend welding, painting, assembly, inspection, etc. Among them, the optical method is characterized by its measurement range, resolution, and response.

It is attracting attention because it has advantages over other methods, such as flexibility and the ability to perform global and microscopic measurements. , a typical method is to use a solid-state image sensor (for example, a COD device) or a PSD (PO8ITION 5ENS).
ITIVE DETECTOR) as a sensor,
This is a method of projecting slit light or spot light onto an object to be measured (workpiece) and measuring the shape, position, etc. of the workpiece from characteristic points (for example, bending points) of the projected image.

FIG. 1 shows an embodiment of the above system, which was announced at the 11th Industrial Robot Symposium (held in Tokyo in October 1981). In the figure, 1 is a near-infrared LED, 2 is a collimating lens for concentrating the light from the near-infrared LED 1 into a spot light (approximately circular parallel light beam), and 3 is a projecting spot light onto a welding work 4. and a galvanometer for scanning the spot light, 5 is a workpiece 4
This spot light image 5 is formed on a two-dimensional PSD sensor 7 via a condensing lens 6. As is well known, the two-dimensional PSD sensor 7 outputs a signal proportional to the center of gravity of the illuminance of the spot light image 5 formed thereon, so that
An axis is provided, and the axis perpendicular to the surface of the two-dimensional PSD sensor 7 is defined as Z.
By setting a coordinate system such as an axis, and determining the positional relationship between the two-dimensional PSD sensor 7, condensing lens 6, and galvanometer 3, and the direction (position) of spot light projection, the above two
The position of the spot light image 5 on the surface of the workpiece 4 can be calculated from the position data of the spot light image 5 on the surface of the dimensional PSD sensor 7 using the principle of triangulation. Therefore, the position of the welding line 8 of the workpiece 4 as shown in FIG. 1 can be easily calculated using a microcomputer or the like based on the position data of the spot light image 5 detected by the two-dimensional PSD sensor 7. If the two-dimensional PSD sensor 7 is used, the center of illuminance of the spot light image 5 is automatically detected, so compared to the method using a COD element, there is no need to worry about image blurring, and the spot position This method has advantages such as not requiring calculations such as line thinning processing for determining the line width, and high-speed detection due to random access.

However, when the spot light 9 is projected onto the slope of the concave workpiece 4 as shown in FIG. On the PSD sensor 7, the D point for the 0 point and the 01 point,
An image of point D1 is detected, and the two-dimensional PSD sensor 7
The position of the center of illuminance at point D'', that is, point Do'' is output. What we want to detect is D relative to the 0 point of spot light 9.
Although it is the position of a point, due to the influence of such deliberate reflection, D
It deviates to the "° point," and the detection error is (D-D). This amount is also greatly affected by the reflective state of the slope.
When using the two-dimensional PSD sensor 71, it is difficult to detect the shape of the slope of the workpiece 4. .

On the other hand, if the workpiece 4 is a particularly thick plate, the value shown in Figure 3 is ±0.
．． It is necessary to detect about 2 gates with zero accuracy.

Therefore, the method using the two-dimensional PSD sensor 7 can only be applied to the measurement of convex objects that are not affected by reflection. There were many restrictions and the measurement accuracy was not sufficient.

Purpose of the Invention The present invention provides a visual sensor that can measure the three-dimensional position and two dimensions of an object by improving the problems of the conventional example (reflection problem and the shape of the spotlight). The purpose is to obtain a spot light position detection device.

Structure of the Invention As a structure for this purpose, the present invention includes a means (1) for setting a spot light, and a means (2) for projecting the spot light onto an object to be measured.
A spot light image composed of a means for dimensionally scanning (Ill), a means for detecting the projection direction of the spot light by the scanning (Ill), and a sensor in which an optical lens and a plurality of one-dimensional photoelectric elements are arranged in parallel. The apparatus includes a detection means (IV) and a sensor output selection means (V) for sequentially selecting the one-dimensional photoelectric element based on the detection data of the means (IIll).

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 4 to 7 of the drawings.

+11 is means for setting the spot light 9, which includes a light emitting section 10, a circuit 11 for controlling the light emitting section 1o, and a lens 12 for focusing the light output from the light emitting section 1o into a spot light.
It consists of - As an example, the light emitting part 1o is near infrared L
ED, semiconductor lasers, gas lasers, etc. are used, but if a laser such as a semiconductor laser is used, the spot of the light spot 9 can be focused smaller than in the case of a near-infrared LED, and the advantage of a single wavelength can be utilized. It is easy to cut out disturbance noise light using an interference filter or the like. The lens 12 is a collimating lens, such as a normal optical lens or a cylindrical optical glass lens whose refractive index is distributed radially from the central axis toward the outer peripheral surface. Next, (n) projects a spot light onto the object to be measured (here, the welding work 4), and the spot light 9 is composed of a light beam 216. for example,
As shown in FIG. 4, the reflecting mirror 13 is connected to a pulse motor as the scanning mechanism section 16, and the other reflecting mirror 14 is connected to an AC4 or DC motor as the scanning mechanism section 16. By driving the drive circuits 17 and 18, the spot light image 5 is moved to the workpiece 4 as shown in the figure.
The image is scanned two-dimensionally. In this case, the pulse motor is used for scanning in the X-axis direction, and the AC or DC motor is used for scanning in the Y-axis direction. In each scanning sequence, a pulse motor is controlled to shift the Y-axis scanning line by a unit length in the X-axis direction every time one scan in the Y-axis direction is completed.

Furthermore, although an example of using a motor to rotate or oscillate the reflecting mirrors 13 and 14 is shown here, other methods other than the motor, such as the use of vibrations of sound g, etc., are also effective and are not limited to this. .

Next, (Ill) is a means for detecting the projection direction of the spot light 9 scanned by the spot light 9 by the means (Ill), and is composed of, for example, a detector 19 and a signal processing circuit 20. be done. Then, as shown in FIG. 4, the signal is converted into a signal necessary for controlling the circuit 21 next to the pulse encoder connected to the mechanism section 16 (AC or DC motor shaft) for scanning in the Y-axis direction. Note that when using servo control using a servo motor or the like for the X-axis direction scanning mechanism section 15, scanning position detection control is of course necessary.

Here, an example is given in which a pulse motor is used, so a detector such as a pulse encoder is not necessary, and the scanning position can be detected in advance.

Next, (lv) is a spot light image detection means for detecting the position of the spot light image projected onto the workpiece 4.

This is composed of an optical lens 22 and a plurality of one-dimensional (tanzak-shaped) photoelectric elements 23 arranged in parallel (horizontally). As the one-dimensional photoelectric element 23, for example, a one-dimensional image sensor, a one-dimensional PSD sensor, or the like can be used. Further, as an optical lens, one having an optical filter effect, for example, a negative lens can be obtained. Next, (V) is a sensor output selection means for sequentially selecting the one-dimensional photoelectric element 23 based on the output signal of the means (1111), and is constituted by a circuit 21 such as an analog signal multiplexer. The output of the selected PSD sensor is output as Vo. If this output Vo is A/D converted and input into the microcomputer, various measurement and recognition processes can be performed.

As described above, especially as a seven-sensor, the one-dimensional photoelectric element 23 is selected in synchronization with the direction of spot light projection, which is superior to the conventional two-dimensional PSD sensor. , the decrease in detection accuracy due to the influence of reflection is significantly reduced.

Further, examples will be specifically explained. First, light source 1o
As a 2577LW semiconductor laser (wavelength 830nm
) is modulated into 10 cities, a collimating lens is used as the lens 12, and the diameter of the spot light is 0.
A pulse motor serving as a scanning mechanism part 15, 16 and a reflecting mirror 1 each attached to the motor.
3.14, the top of the welding work 4 as shown in Fig. 5 is
Scan dimensionally. The rotation angle of the reflecting mirror 14 for scanning in the Y-axis direction is 5 degrees, which is approximately 2 degrees during scanning on the 4 surfaces of the workpiece.
This corresponds to 0 mm. The rotation angle of the reflecting mirror 140 is detected by a pulse encoder (4000 pulses/T) in the detector 19 directly connected to the DC motor, and by the encoder pulse quadruple frequency circuit in the circuit 2o.
Detects with a resolution of 5°.

In addition, in the circuit 2o, based on this detection pulse, a signal is sent to an analog multiplexer as a circuit 21 every 0.5 degrees of rotation angle of the reflecting mirror 14, and 10 one-dimensional PSD sensors (IX10 tone) are arranged. P of the one-dimensional photoelectric element 23
Select the output of the SD sensor. On the other hand, the X-axis scanning pulse motor rotates the reflecting mirror 13 by 0.5° every time one Y-axis scan is completed, and controls this at a 5° cycle. Note that the optical lens 22 includes a normal convex lens and an 8oO~8
An interference filter that allows 85% or more of light with a wavelength of 50 nm to pass through was used in combination. In addition, in Figure 6, Shinobu, -201
11111, ff12=15111111, Q3=
6rrrm, n4=2mm with Te, and reflector 14
The distance from the welding workpiece 4 to the flat plate part was about 150 mm.

An example of the detection data obtained in this example is shown in Figure 6 (
). The wavy lines are reference values corresponding to the actual groove shape, and the black dots are detected data. Note that the one-dimensional photoelectric element 2
The output from the PSD sensor (3) is a current signal, so it is converted into a current voltage, amplified, and then passed through a 10mm bandpass filter, A/D converted, and input into the microcontroller to be converted into a one-dimensional PSD. This sunspot data is converted into a position signal of the spot light image on the sensor surface.

This revealed that the detection accuracy in the groove gap can be within ±0.2 degrees, that there is almost no influence of reflection, and that the groove shape can be detected with an accuracy of ±0.2 degrees. Next, FIG. 6(b) shows the result when a conventional two-dimensional PSD sensor is used as the one-dimensional photoelectric element 23 (therefore, means (fill and (Vl) are unnecessary), but the spot light inside the groove is It is clear that the detection of the groove shape as well as the groove gap is extremely inaccurate due to the influence of reflections.

Next, FIG. 7 shows an example in which the device of the present invention is applied to detecting the welding start point 24 and weld line 8 of a fillet weld joint. Conventional 1
With the dimensional scanning method, it was extremely complicated and took a lot of time to detect this welding start point 24, but with this device, a single two-dimensional scan can achieve a detection accuracy of 2 mm in the X-axis direction. , the detection accuracy in the Y-axis direction was within the 0.4 range. Detection time was about 2 seconds.

In this case, after detecting the welding start point 24,
The detection time is reduced by half or less during scanning in the Y-axis direction.

Effects of the Invention As described above, according to the present invention, it is possible to reduce the influence of secondary reflection on objects of any shape to an almost negligible level, and to reduce optical noise by reducing the spot diameter using a semiconductor laser or by using an interference filter, etc. This effect makes it possible to extremely accurately measure the three-dimensional position, nine dimensions, etc. of an object. Furthermore, the two-dimensional scanning function allows two-dimensional distance information to be obtained, and detection of welding start, end points, corner points, etc. can be greatly speeded up. Furthermore, by combining this device with a control circuit such as a microcomputer, it is possible to construct a high-performance, highly reliable, and low-cost industrial visual sensor.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a conventional three-dimensional object detection method,
FIGS. 2 and 3 are explanatory diagrams showing the influence of secondary reflection in the conventional example, FIG. 4 is an explanatory diagram of a spot light position detection device in an embodiment of the present invention, and FIG. 6 is a perspective view of a workpiece. , 6th
Figures (a) and (b) are characteristic diagrams showing the results of groove shapes, respectively, and Fig. 7 is a perspective view showing an example of detecting the welding start point of a fillet weld joint. 4...Welding workpiece, 8...Welding line, 9
...Spot light, 1o... Light emitting part, 1
1...Circuit, 12...Lens, 13.
14...Reflecting mirror, 15...X-direction scanning mechanism section, 16...Y-direction scanning mechanism section, 17
．． 18...Drive circuit, 19...Detector, 2゜...Signal processing circuit, 21...Circuit, 22...Optical lens , 23...1
Dimensional photoelectric element, 24...Welding start point, (11.
...Means for setting spot light, (II)...
. . . Means for scanning the spot light two-dimensionally, (I[[
)...Means for detecting the direction of spot light projection,
(IV)...Spot light image detection means, (V).
...Sensor output selection means. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 41! l Figure 5 Figure 6 (OL) Figure 7

Claims (5)

[Claims] (1) A means (1) for setting a spot light, and a means (n) for projecting the spotlight onto an object to be measured and scanning it two-dimensionally.
), a means (III) for detecting the projection direction of the spot light by the scanning, and a spot light image detecting means (III) consisting of a sensor having an optical lens and a plurality of one-dimensional photoelectric elements arranged in parallel. Based on the detection data of means (Ill),
A spot light position detection device comprising sensor output selection means (V) for sequentially selecting the one-dimensional photoelectric elements. (2) The spot light position detecting device according to claim (1), wherein the means (1) for setting the spot light comprises a semiconductor laser and a collimating lens. (3) The spot according to claim (1), wherein the means (II) for two-dimensionally scanning the spot light is constituted by a reflecting mirror and a mechanism unit that rotates or swings the reflecting mirror. Optical position detection bag device. (4) The spot light position detection device according to claim (1), wherein the one-dimensional photoelectric element of the spot light image detection means (IV) is a PSD sensor. (5) The optical lens of the spot light image detection means (transmission) is
The spot light position detection device according to claim (1), which is a lens having an optical filtering effect.